Fantastic article by Arlene Prunkl at http://penultimateword.com/fiction/dialect-in-dialogue-how-to-write-authentic-dialect-and-foreign-accents/ (linked to in the External Link):

Dialogue in fiction: Part I – How to write authentic dialects and foreign accents

Of the many things to master when writing dialogue in fiction, creating authentic dialects and natural-sounding foreign accents for your characters is possibly the most challenging. If you don’t get the accent just right, you risk having your characters come off looking like caricatures. Worse, you alienate readers, who don’t like being slowed and confused by a lot of nonstandard spellings. And worst of all, you may appear to be discriminatory or even ignorant by inadvertently stereotyping your characters through how you portray their accents. In this post, I’ll take a look at ways to make your characters’ English dialects and foreign accents as realistic as possible without reducing them to goofy stereotypes.

The English language is the lingua franca of our modern world. All over the world, people in foreign countries are learning English to help them with communications in business, finance, medicine, science, technology, and many other fields. The number of people in the world speaking English with a foreign accent has never been greater. Add to that the fact that in virtually every part of the English-speaking world, different regions and ethnicities speak English differently, and chances are you have at least one character in your novel who speaks with an accent.

Accents are caused by the influence of a speaker’s native language or native dialect on the English words they speak. The differences can be found in pronunciation, diction (word choice), syntax (word order), grammar (how parts of speech are structured), and idiom (peculiarities of certain phrases). Accent and dialect can convey differences in ethnicity, geography, demographics, class, education, and culture. Even standard English is a dialect.

Nonstandard spellings and contractions
When you’re reading a novel with characters who speak with foreign accents or in dialect, how much misspelling can you tolerate in their dialogue? Probably not much—today’s readers don’t have much patience for puzzling out phonetic spellings and odd contractions. (A contraction is any word or set of words that uses an apostrophe to replace any dropped letter or letters: ’Tis th’ night b’fo’ Christmas, an’ I’s fixin’ t’go carolin’ wi’ y’all.)

This is quite a change from 150 years or so ago. Back in the 19th century, it was in vogue to capture every scrap of phonetic pronunciation to render a character realistic. Twain, Dickens, Harriet Beecher Stowe are a few authors who took pains to achieve this. Look at this example from Huckleberry Finn (1884), and see if you don’t find it just slightly annoying:

Oh, Huck, I bust out a-cryin’ en grab her up in my arms, en say, ‘Oh, de po’ little thing! De Lord God Amighty fogive po’ ole Jim, kaze he never gwyne to fogive hisself as long’s he live!’ Oh, she was plumb deef en dumb, Huck, plumb deef en dumb—en I’d ben atreat’n her so!

Most readers today become annoyed quickly by this kind of writing, where almost every word needs to be examined to decipher its pronunciation and meaning. It’s distracting; it slows readers down, pulls them out of the story, out of the “fictional dream” you worked so hard to create. They may end up paying less attention to what’s being said than to how it’s being said.

Nobody speaks English the way it’s spelled
Everybody who speaks English has an accent to others not in their region or ethnic group. And almost nobody truly pronounces English the way it’s spelled. Even someone with little trace of an English accent might say, “I wanned us t’go to th’movie, bu’ we godda do th’shoppin’ first.” Not even the Queen’s English comes out the way it’s spelled (far from it—think about all those dropped Rs). Among some of the most overdone written accents and dialects are “Southernese” from the American South, African American English, British cockney, and Scottish or Irish brogue.

As writers, we wouldn’t think of spelling of all our characters’ dialogue phonetically, so why do we do it only with characters who speak in a dialect or with an accent that we don’t consider “standard”? It can imply that those characters are inferior, ignorant, less educated (or not at all), less intelligent—in other words, it makes a parody of them, which is the very opposite of the original goal of making them realistic and believable. (In Gone with the Wind, Margaret Mitchell gave only her black characters phonetic spellings, wrongly implying they were inferior, even though the blacks and whites spoke a phonetically similar dialect.)

So what can you do to avoid falling into this trap with your foreign-accented characters or those who speak in a pronounced dialect? Let’s take a look.

Moderation is essential
Be conservative. You don’t need to spell out every diphthong and dropped “g.” Less is more. Whatever combination of techniques you use to render an accent or dialect in dialogue, use them with a light hand. It’s tempting, because it’s easiest, to write a dialect or accent phonetically, but if you overdo this, you’ll confuse, bore, insult, or possibly even lose your readers.

Here’s another example of an overdone accent—this one a Southern black accent from Harriet Beecher Stowe’s Uncle Tom’s Cabin. Tom’s Aunt Chloe says to him:

S’pose we must be resigned; but oh Lord! how ken I? If I know’d anything whar you’s goin’, or how they’d sarve you! Missis says she’ll try and ’deem ye, in a year or two; but Lor! nobody never comes up that goes down thar! They kills ’em! I’ve hearn ’em tell how dey works ’em up on dem ar plantations.

Most readers today simply don’t have the tolerance for all those misspellings and contractions.

To achieve moderation when writing accents, first, do some careful research on your character’s particular accent or dialect. Check out other books with similar characters. Then choose just half a dozen or so nonstandard spellings and contractions, and use them consistently. Diana Gabaldon does this well with believable Scottish brogue in her novel Outlander. Just a few well-chosen words bring her character to life realistically: aye (yes), nae (no), ye (you), dinnae (didn’t), canna (cannot), ’twas (it was), laird (lord). Here is an excerpt:

There was nae doubt, ye see, of Colum’s courage, nor yet of his mind, but only of his body. ’Twas clear he’d never be able to lead his men into battle again. . . . So a suggestion was made that Colum be allowed to become laird, as he should in the ordinary way, and Dougal be made war chieftain, to lead the clan in time of battle.

Rely more on diction, syntax, and idiom
Diction is word choice; syntax is word order. An idiom is a native expression, one that usually doesn’t make sense when non-native speakers try to analyze the individual words. Rather than overusing nonstandard spellings and contractions, it’s much more effective, in most cases, to use diction, syntax, and idiom to convey the accent of a non-native speaker of English.

Often, in other languages, words have different meanings and go in a different order from what we’re used to in English. This doesn’t make them wrong or inferior. In fact, it shows our own ignorance as native users of English if we don’t recognize this in our fictional characters’ accented speech. (One interesting tidbit I learned in my research is that Appalachian speech patterns, which many people tend to equate with a lack of education and backwoods isolation, may derive from the formal Elizabethan English of early settlers from the British Isles.)

Diction (word choice)
Different dialects use different words to convey the same meaning, or the same word to convey a different meaning. This can be as simple as Brits ordering chips while North Americans order French fries. And North American chips are crisps to Brits. Another less common example: Jamaicans don’t have a past tense for the word come. So if they say, “She come to my house yesterday,” it’s perfectly grammatically correct for them, not an indicator of class or education.

In African-American English, it’s not uncommon to hear the word be used before a verb: “He be going to work.” In fact, this is not an uneducated auxiliary verb that should be is; it’s the way the African-American dialect expresses an ongoing or continual action. The be means “He goes to work every day.” Removing the be means the action is only happening right now, not habitually. Yet when speakers of standard English hear this, it’s often mistaken for a lack of education or lazy speech. (Linguists refer to this as the “habitual be.”)

Syntax (word order)
Several Indian dialects end their sentences with verbs, so instead of saying “She doesn’t know that,” it’s natural for a Hindi character to say it in English as “That is not for her to be knowing.” In Spanish and French, adjectives typically follow the noun instead of preceding it, so you’d be more likely to hear a native Spanish or French speaker say, for la casa blanca or la maison blanche, “the house is white” rather than “the white house.” And in German, Spanish, and French, adverbs sometimes follow verbs rather than precede them.

Examples of how syntax and diction work in different dialects:
→ North American English: He comes home a lot.
→ British: He comes home quite often. (Or, he quite often comes home.)
→ African American: He be coming home.
→ East Indian: Often it is home that he comes.
→ German: He comes often home.
→ French: He comes often home.
→ Jamaican: He come home for some time now.
→ Creole: He returns home often.

Idioms
An idiom is an expression, a combination of regular words, that is unique to a particular dialect or language and may not make sense to any other. For example, do you think you would hear a native Slavic speaker say, “It’s raining cats and dogs”? Learn the idioms of your foreign character’s native dialect or language and apply them judiciously. Perhaps have your character accidentally mix up an English idiom for a little fun (“It’s raining cats and chickens”), but be careful not to make him or her seem silly.

Verbs
As most of us who’ve ever attempted to learn another language know, verb conjugation can be one of the most difficult things to master. Most non-native English speakers will learn the present tense but will take much longer to pick up the various more complex verb forms and tenses. So when writing realistic dialogue for your foreign characters, use the present tense more often than not, even when it’s incorrect (though use moderation with this, too). Instead of writing, “If I go swimming five times this week, I will have had a great workout,” write “I swim five times this week, so I have great workout.”

Some final tips
1. Try writing all your characters’ dialogue in standard English first. Get down what they’re saying, then worry about how they’re saying it. Study their accents and dialects for regional and foreign differences in syntax and diction, then go back and make small changes based on what you’ve learned.

2. It’s especially effective to include occasional foreign words, words that readers will recognize immediately as the character’s native language. Greetings like bonjour and adios, and terms of endearment like mon chéri, mi carina, and mein lieber are good choices because their meaning can be gleaned from the context. Again, don’t overdo this (which I may be guilty of here, just for the purpose of demonstrating):
→ “Tomorrow—it will be magnifique,” Cécile said as Bob got in the car. “Au revoir, mon chéri.”
→ “Adios, mi amiga,” Bonita said, waving. “I see you mañana.”

3. Occasionally, you can leave the dialogue in standard English and simply describe the accent to readers.
→ “Let’s go grab a pizza. Maybe we’ll get the Caesar’s salad too,” Giovanni said in a thick Italian accent.

4. Drop the indefinite or definite articles (a and the), or mix them up.
→ “We go eat pizza, maybe we get Caesar salad too?” Giovanni said.
→ “Why you not have the beer with a spaghetti, you not thirsty?” he asked.

5. Break some English grammar rules. For example, use comma splices or nonstandard grammar, just as I did in the two examples just above. At the same time, learn the rules of your characters’ native language or dialect so you know how to apply them in when translated into English.

6. Be consistent. A character who says “I ain’t gonna let them mofos git me” shouldn’t show up in a later chapter saying “I simply won’t allow those nasty people to bother me.”

7. Read out loud. Make sure the dialogue has rhythm and consistency, even in its oddities. Then enlist the help of friends and others who are both familiar and unfamiliar with the foreign languages and dialects you’re using. Do the characters’ voices sound realistic to them?

8. Use a combination of all the techniques described here. The most effective dialogue combines appropriate idioms, jargon, and foreign words, a few misspellings, a few contractions, and careful attention to word choice, word order, tone, and rhythm.

9. Be aware of subtleties in speech patterns as well as word choice. For example, a British person would likely say “I’ve not seen the postman come round in days,” rather than the more North American “I haven’t seen the mail lady come by in days.”

Give your characters respect, dignity, authenticity
Respect your characters. Don’t turn them into a parody of themselves by overdoing any of these techniques. Conservative use of all these techniques will give them dignity and authenticity. If you set the tone with just a few well-chosen applications of these techniques, it won’t even be necessary to repeat them very often. Handling dialogue accents with care and moderation means you won’t look as if you’re disrespecting your characters’ ethnicity, regionalisms, culture, or education level—and, in turn, your readers will respect you, the author. Your ultimate goal is to give your readers authentic, realistic characters while still giving them a smooth and pleasant reading experience.